1. Field of the Invention
This invention relates the field of chemistry and particularly to the field of producing molecules in excited states, such as singlet molecular NF, abbreviated to NF*.
2. Description of the Prior Art
A molecule is in an excited electronic state when the arrangement of its electrons about the nucleus places it in an energy state about its usual ground state. Molecules such as NF are known to exist in several different energy states. The two lowest excited electronic states for NF are the NF*(a.sup.1 .DELTA.) and the NF*(b.sup.1 .SIGMA..sup.+) states.
Prior art methods of producing the NF* states are by microwave discharge of the NF.sub.3 molecule or by chemical means. The only known chemical means of producing NF* is by reacting NF.sub.2 with H, D, or CH.sub.3 to produce NF*(a.sup.1 .DELTA.), i.e. H+NF.sub.2 .fwdarw.NF(a.sup.1 .DELTA.). NF*(b.sup.1 .SIGMA..sup.+) can then be produced from NF*(a.sup.1 .DELTA.) via energy transfer from O.sub.2 *(.sup.1 .DELTA.g), I*(5 .sup.2 P.sub.1/2), or HF(v.gtoreq.2) as described by Herbelin and Cohen in CHEMICAL PHYSICAL LETTERS, Vol. 20, page 605 (1973).
Both the prior art methods of producing NF* have problems which severely limit their usefulness. The microwave discharge method produces the NF* in low concentrations. Although higher concentrations of NF* are produced by the known chemical reaction of NF.sub.2, the hydrogen used in the reaction quenches the NF*. Further, it is difficult to obtain the atomic hydrogen and utilize it before it recombines to form molecular hydrogen.
The NF*(a.sup.1 .DELTA.) and NF*(b.sup.1 .SIGMA..sup.+) states are metastable, with radiative lifetimes of approximately 1 second and 15 mseconds, respectively. Emission from these states occurs within rather narrow bandwidths, the a.fwdarw.x transition occurring at 874.2 nm and the b.fwdarw.x transition at 528.8 nm. NF*(a.sup.1 .DELTA.) is known to react with vibrationally excited HF, abbreviated to HF , or any of several other known transfer agents to pump NF* (a.sup.1 .DELTA.) to the NF* (b.sup.1 .SIGMA..sup.+) state. This reaction has very attractive features for a chemical laser because it involves reagent which, in view of the present invention, are readily available and can be produced in relatively high concentrations. Additionally, the reaction produces simple species which should not be deleterious to the operation of a laser. Thus, the molecule NF* (a.sup.1 .DELTA.) has practical utility as a pumping reagent in a chemical laser.